Heat sink clip assembly

ABSTRACT

Disclosed is a heat sink clip assembly comprising a frame and a clip for securing and aligning a heat sink with an electronic device package. The frame includes a cavity for receiving the electronic device package with the leads thereof exposed for mounting on a printed circuit board or the like. A resilient heat sink clip is removably engaged with a pair of latching members on the perimeter of the frame. The clip includes means for releasably gripping the heat sink. The heat sink is urged by the heat sink clip into intimate thermal contact with the electronic device package for dissipation of heat therefrom.

FIELD OF THE INVENTION

This invention relates generally to apparatus for securing electroniccomponents together. More particularly, it relates to apparatus for usein securing a heat sink to an electronic device package.

BACKGROUND OF THE INVENTION

For purposes of this disclosure, a heat sink is any body of metal orlike material placed in contact with an electronic device package fortransferring heat through conduction from the semiconductor devicecontained in the electronic device package and rapidly dissipating suchheat to the environment. One type of electronic device package is knownas a gate array. A gate array includes a relatively thin square orrectangular housing containing a semiconductor device. A plurality ofrigid leads are electrically connected to the semiconductor device andextend downwardly from a lower surface of the housing. The gate array ismounted on a printed circuit board by inserting each of the leads intoan aligned preformed hole in the printed circuit board and soldering thelead therein.

Finned heat sinks have been found to be particularly effective when usedwith gate arrays. A finned heat sink consists of a central post having aplurality of spaced fins extending radially from the post. When one endof the post is mounted on the gate array housing, heat generated by thesemiconductor device contained therein is conveyed through the post anddissipated into the environment by the large surface area presented bythe fins.

Various means have been used in the past to attach a heat sink inintimate thermal contact with an electronic device package. It is knownto glue or otherwise adhesively attach a heat sink to an electronicdevice package such as a gate array. However, assembly of a sink to theelectronic deice package is messy, tedious, labor intensive andtherefore expensive and it is difficult to accurately align the heatsink with the electronic device package. This is particularly a problemwhen attaching a finned heat sink to a gate array. Many of the commonlyused adhesives emit fumes or otherwise constitute an undesirable healthhazard. Frequently, it is necessary to cure the glue at an elevatedtemperature for extended periods of time, further increasing themanufacturing costs. It is also sometimes desirable to remove the heatsink from the electronic device package for repair or replacement. Thisis extremely difficult, if not impossible, to accomplish when the heatsink is adhesively mounted on the electronic device package.

SUMMARY OF THE INVENTION

The present invention provides a heat sink clip assembly for securing aheat sink to an electronic device package for dissipation of heattherefrom. The heat sink clip assembly includes a frame having cavityfor receiving the electronic device package and a pair of flanges forreleasably securing the heat sink clip to the frame. The heat sink clipis also adapted to releasably grip the heat sink so as to align andsecure the heat sink in intimate thermal contact with the electronicdevice package. The invention therefore provides the advantages ofimproved heat sink clip assembly for use in securing a finned heat sinkin intimate thermal contact with a gate array which mechanically securesthe heat sink to the electronic device package. The structure of theinvention automatically aligns the heat sink with the electronic devicepackage and is quickly and easily assembled and disassembled from theheat sink and electronic device package.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features and advantages ofthe invention as well as others which will become apparent to thoseskilled in the art are obtained and can be understood in detail, a moreparticular description of the invention briefly summarized above may behad by reference to the embodiments thereof which are illustrated in theaccompanying drawing, which drawing forms a part of the specificationand in which like numerals depict like parts in the several views. It isto be noted, however, that the appended drawing illustrates onlypreferred embodiments of the invention and is therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is an exploded perspective view of a heat sink clip assemblyaccording to one embodiment of the invention.

FIG. 2 is a side elevational view of the heat sink clip assembly of FIG.1.

FIG. 3 is a top plan view of the frame of FIG. 1.

FIG. 4 is a fragmentary sectional view taken along plane 4--4 of FIG. 3.

FIG. 5 is a top plan view of the heat sink clip of FIG. 1.

FIG. 5a is a perspective view of an alternate embodiment of the heatsink clip of FIG. 5.

FIG. 6 is a side elevational view of the heat sink clip of FIG. 1.

FIG. 7 is an end view of the heat sink clip of FIG. 1.

FIG. 8A is a fragmentary sectional view of the heat sink clip and finnedheat sink assembly of FIG. 2 taken immediately above the heat sink clip.

FIG. 8B is a magnified fragmentary view of the heat sink clip of FIG. 2engaged with a latching member.

FIG. 9 is an exploded view of an alternate embodiment of the heat sinkclip assembly of the invention.

FIG. 10 is a perspective view of the heat sink clip assembly of FIG. 9.

FIG. 11 is a top plan view of an alternate embodiment of the heat sinkclip of FIG. 9.

FIG. 12 is a fragmentary side view of the heat sink clip of FIG. 11.

FIG. 13 is a fragmentary sectional view of a heat sink clip assemblyusing the clip of FIG. 11.

FIG. 14 is an exploded perspective view of another alternate embodimentof the heat sink clip assembly of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1 and 2, the reference numeral 10 generallyindicates the heat sink clip assembly of this invention. The heat sinkclip assembly is used in conjunction with gate array 12 having a squareor rectangular housing 14 and plurality of downwardly depending leads 16projecting from a lower surface (not shown) of the housing. Pad 18 isformed on the upper surface 20 of housing 14 and is in thermal contactwith a semiconductor device (not shown) contained within the housing forrapidly transferring heat exteriorly of the gate array package. Finnedheat sink 24 is provided for use with gate array 12. The finned heatsink 24 includes a post 26 having one end in intimate thermal contactwith pad 18 of the gate array. However, it is recognized that certaingate array designs do not incorporate a pad. Therefore the finned heatsink is placed in direct contact with the upper surface of the gatearray housing. A plurality of longitudinally spaced fins 28 projectradially from the post and present a large collective surface area fordissipating heat from the gate array through the heat sink.

Frame 32, shown in more detail in FIGS. 3 and 4, includes cavity 34 forreceiving the gate array 12 in close confinement about the side edges ofthe gate array housing. The frame is preferably constructed ofelectrically insulating material such as nytron or delrin and is easilymolded or manufactured to conform to a desired shape. The frame includesshoulder 36 extending inwardly into cavity 34 so as to contact the lowersurface and side edges of the gate array housing and support the gatearray in a predefined position within the cavity. Further, the inneredge of the cavity may include a plurality of semicircular notches 38.Each of the notches 38 is aligned with one of the outermost downwardlydepending leads 16 of the gate array when the gate array is located inthe cavity of the frame. The notches 38 assist in aligning the gatearray housing with respect to the frame. A pair of spaced latchingmembers 40 are formed on the perimeter of the frame. Specifically, thelatching members 40 are located on opposite corners of the frame andeach includes an outwardly projecting tooth 42 with inclined surface 44.If desired, the latching members may be formed on opposite sides of theframe rather than on opposite corners as illustrated.

Heat sink clip 50, shown in more detail in FIGS. 5-7, is provided tosecure the finned heat sink 24 to the gate array 12. The heat sink clipis constructed of resilient, preferably metallic, material and includesan elongated body 52 terminating at both ends in downwardly dependingflanges 54. Each flange includes an opening 56 and an outwardly flaringlip 58. The body includes an intermediate arcuate section 60 definingaperture 62. The aperture has an internal diameter at left equal to theouter diameter of the post 26 of the finned heat sink 24. Tapered edges64 lead into the aperture from one side of the heat sink clip.

In assembled condition the gate array 12 is positioned in the cavity 34of the frame 32 with the leads 16 of the gate array extending downwardlyfor presentation to aligned preformed holes (not shown) in a printedcircuit board (not shown). As is shown in greater detail in FIG. 8A, theheat sink clip 50 is inserted between two fins of the finned heat sinkso that post 26 is captured within aperture 62 of the arcuate section 60of the clip. The finned heat sink is then brought downwardly indirection 66 into contact with pad 18 of the gate array housing. Theflanges 54 of the heat sink clip are each aligned with one of thelatching members 40 of the frame. By simultaneously deflecting theflanges of the heat sink clip downwardly as the heat sink is loweredtoward the frame, the flanges 54 are each brought into engagement withone of the latching members 40. Specifically, the lips 58 of the flangesencounter the inclined surface 44 of the latching member and deflect theflanges outwardly until the openings 56 encounter the bottom of theteeth 42. The flanges then assume a relaxed position, as shown in FIG.8B, with the teeth 42 caught in openings 56 and securing the clip to theframe with the finned heat sink in intimate thermal contact with pad 18of the gate array.

Preferably, the heat sink clip 50 is inserted between a pair of fins ata sufficient height above the gate array so that the clip exerts aresilient force in direction 66 on the finned heat sink urging it intointimate thermal contact with the pad. In such a position and as shownin FIG. 2, the body of the heat sink clip assumes a bowed or concaveposture. The heat sink clip assembly may be quickly and easilydisassembled by disengaging the flanges 54 of the heat sink clip fromthe latching members 40 of the frame and withdrawing the finned heatsink from the gate array. Another advantage of the heat sink clip ofthis invention is that the heat sink clip and frame cooperate toautomatically align the finned heat sink with the gate array, thusreducing assembly time and expense while maintaining the heat sink inalignment even if the assembly is subjected to mechanical vibration orother forces. Location of the latching members 40 at opposite corners ofthe frame is advantageous in situations where two or more gate arraysare mounted on a printed circuit board or the like in close proximity.In such a case the distance between the frames of adjacent heat sinkclip assemblies may be minimized by offsetting the opposing latchingmembers. That is, the latching members are located on opposite cornersof adjacent frames so that the distances which the latching membersprotrude from their respective frames at least partially overlap insteadof being additive. However, such an arrangement is not required for theheat sink clip assembly of this invention.

An alternate embodiment 50' of the heat sink clip is shown in FIG. 5A.The heat sink clip 50' includes an elongated body 52' terminating ateither end in downwardly depending flanges 54. Each of the flangesincludes an opening 56 and an outwardly flaring lip 58 as in theembodiment of FIGS. 5-7. The body 52' includes an arcuate section 60'defining aperture 62'. The aperture 62' has an internal diameter atleast equal to the outer diameter of the post 26 of the finned heat sink24. Tapered edges 64' lead into the aperture from one side of the heatsink clip. However, in this embodiment the aperture 62' encompasses agreater portion (i.e. at least 270°) of the periphery of the post of thefinned heat sink and thus more securely mounts the finned heat sink incontact with the gate array. In all other respects, this alternateembodiment is as described above with respect to the embodiment of FIG.5.

An alternate embodiment of the heat sink clip assembly is shown in FIGS.9-13. As in the embodiment of FIGS. 1-8, the heat sink clip assembly 110is used in conjunction with gage array 112 having a rectangular housing114 and a plurality of downwardly depending leads 116 projecting from alower surface (not shown) of the housing. Pad 118 is formed on uppersurface 120 of the housing 114 and is in thermal contact with asemiconductor device (not shown) contained within the housing forrapidly transferring heat from the gage array housing. Finned heat sink124 is provided for use with gage array 112. The finned heat sink 124 issubstantially similar to finned heat sink 24 and includes a post (notshown in FIGS. 9 and 10) having one end in thermal contact with pad 118of the gate array. A plurality of longitudinally spaced fins 128 projectradially from the post and present a large collective surface area fordissipating heat from the gate array through the heat sink.

Frame 132, shown in more detail in FIGS. 3 and 4, includes cavity 134for receiving the gate array 112 in close confinement about the sideedges of the gate array housing. The frame is preferably constructed ofelectrically insulating material such as nytron or delrin and is easilymolded or manufactured to conform to a desired shape. Frame 132 includesshoulder 136 extending inwardly into cavity 134 so as to contact thelower surface of the gate array housing and support the gate array in apredefined position within the cavity. Further, the inner edge of thecavity may include a plurality of semicircular notches 138. Each of thenotches 138 is aligned with one of the outermost downwardly dependingleads 116 of the gate array when the gate array is located in the cavityof the frame. The notches 138 assist in aligning the gate array housingwith respect to the frame. A pair of spaced latching members 140 isformed on the perimeter of the frame. Specifically, the latching members140 are located on opposite sides of the perimeter of the frame and eachincludes an outwardly projecting tooth 142. If desired, the latchingmembers may be formed on opposite corners of the frame rather than onopposite sides as illustrated in the embodiment of FIGS. 1-8.

Heat sink clip 150 is provided to secure the finned heat sink 124 to thegate array 112. The heat sink clip is constructed of resilient materialand includes an elongated rod-like body 152 terminating at both ends indownwardly deflected arcuate ends 154 and 156.

The embodiment of heat sink clip assembly shown in FIGS. 9-13 isassembled similarly to that shown in FIGS. 1-8. Gate array 112 ispositioned in cavity 134 of frame 132 with the leads 116 of the gatearray extending downwardly for presentation to aligned preformed holes(not shown) in a printed circuit board (not shown). The heat sink clip150 shown in FIGS. 9 and 10 is placed over the uppermost fin of thefinned heat sink 124. The finned heat sink is then urged into contactwith the pad 118 (not shown in FIG. 10) of the gate array housing. Theends 154 and 156 of the heat sink clip are each aligned with one of thelatching members 140 of the frame 132. By simultaneously deflecting theends 154 and 156 of the heat sink clip downwardly toward the frame, theends are each brought into engagement with one of the latching members.Specifically, the ends encounter the teeth 142 of the latching member.The ends then assume a position engaging the teeth and securing the clipto the frame with the finned heat sink in contact with the gate array.

In an alternate embodiment 150' of the heat sink clip (shown in FIGS.11-13), the body 152' includes an arcuate section 160). The arcuatesection defines aperture 162 having an internal diameter ("d" in FIG.11) at least equal to the outer diameter of the post 126 (shown in FIG.13) of the finned heat sink 124. The heat sink clip 150' of FIGS. 11-13is inserted between two fins 128 of the finned heat sink 124 so that thepost 126 is captured within aperture 162 of arcuate section 160 of theclip. Preferably, the heat sink clip 150' is inserted between a pair offins at a sufficient height above the gate array so that the clip exertsa resilient downward force on the finned heat sink urging it intointimate thermal contact with the pad.

FIG. 14 shows another alternative embodiment 210 of the heat sink clipassembly of this invention. The heat sink clip of FIG. 14 is used inconjunction with gate array 212 having a rectangular housing 214 and aplurality of downwardly depending leads (not shown) projecting from alower surface of the housing. Pad 218 is formed on upper surface 220 ofthe housing 214 and is in thermal contact with a semiconductor device(not shown) contained within the housing for rapidly transferring theheat from the gate array package. Finned heat sink 224 is provided foruse with gate array 212. The finned heat sink 224 includes a post (notshown) having one end adapted for intimate thermal contact with pad 218of the gate array. A plurality of longitudinally spaced fins 228 projectradially from the post and presents a large collective surface area fordissipating heat from the gate array through the heat sink.

Frame 232 includes a cavity 234 for receiving the gate array 212 inclose confinement about the side edges of the gate array housing. Theframe includes a shoulder (not shown) extending inwardly into cavity 234to contact lower surface and side edges of the gate array housing inclose confinement and support the gate array in a predefined positionwithin the cavity. Further, the inner edge of the cavity may include aplurality of semicircular notches (not shown). Each notch is alignedwith one of the outermost downwardly depending leads of the gate arraywhen the gate array is located in the cavity of the frame. The notchesassist in aligning the gate array housing with respect to the frame. Apair of spaced latching members 240 (only one of which is shown in FIG.14) is formed on the perimeter of the frame. Specifically, the latchingmembers 240 are located on opposite sides of the frame and each includesan outwardly projecting tooth 242 having an inclined surface 244. Ifdesired, the latching members may be formed on opposite corners of theframe rather than on opposite sides as illustrated in the embodiment ofFIGS. 1-8.

Heat sink clip 250 is provided to secure the finned heat sink 224 to thegate array 212. The heat sink clip 250 is constructed of resilient,preferably metallic, material and includes body 252 terminating at bothends in downwardly depending flanges 254. Each flange 254 includes anopening 256 and an outwardly flaring lip 258. Aperture 262 is defined inthe body 252 of the heat sink clip having a diameter greater than theouter diameter of the post of the finned heat sink 224. Four tabs 264extend upwardly from the body of the heat sink clip opposite the flangesand each of the tabs includes an inwardly projecting tang 266.

In assembled condition the gate array 212 is positioned in the cavity234 of the frame 232 with the leads of the gate array extendingdownwardly for presentation to aligned preformed holes (not shown) in aprinted circuit board (not shown). The heat sink clip 250 is presseddown onto frame 232 with the flanges 254 aligned with one of thelatching members 240. The flanges 254 are each brought into engagementwith one of the latching members. Specifically, the lips 258 of theflanges encounter the inclined surface 244 of the latching member and todeflect the flanges outwardly. The flanges then assume a relaxedposition with the teeth caught in the openings and securing the heatsink to the frame with the finned heat sink in contact with the gatearray. The finned heat sink is then brought down into contact with thepad 218 of the gate array housing and the fins 228 of the heat sinkencounter the tabs 264 of the heat sink clip. The tabs are deflectedoutwardly as the heat sink is lowered onto the gate array.

When the heat sink is mounted on the pad of the gate array, the tabs 264spring inwardly and return to a relaxed position with the respectivetangs 266 in contact with the upper side of one of the fins. The finnedheat sink is thus automatically aligned and secured against lateral orupward movement with respect to the gate array. The heat sink clip 250simultaneously exerts a resilient downward force on the finned heat sinkurging it into intimate thermal contact with the pad. The heat sink clipassembly may be quickly and easily disassembled by disengaging the endsof the heat sink clip from the latching members of the frame andwithdrawing the finned heat sink from the gate array. Alternatively, thefinned heat sink 224 may be preassembled to the heat sink clip 250 byengagement with the tabs 264 as herein described and the sub-assemblythen mounted on the frame with the post of the finned heat sink incontact with the pad 218 of the gate array 212 by engaging the flangesof the heat sink clip with the latching members 240 of the frame.

Although the invention has been disclosed above with regard toparticular and preferred embodiments, these are advanced forillustrative purposes only and are not intended to limit the scope ofthis invention. For instance, although the heat sink clip assembly hasbeen illustrated in use with a finned heat sink and gate array, theinvention is applicable for use with other heat sink designs as well asother types of electronic device packages. It is to be understood,therefore, that various changes and modifications may be resorted towithout departing from the spirit and scope of the invention as definedby the appended claims.

What is claimed is:
 1. Apparatus for mounting a heat sink having aplurality of spaced fins extending radially from a central post on anenclosed and sealed electronic device package having a plurality ofleads extending substantially parallel from one surface thereofcomprising:(a) electrically insulating frame means having an open cavityadapted to receive and support an electronic device package about theperiphery thereof with the leads extending from .[.the.]. .Iadd.said.Iaddend.device package through said open cavity and a pair of spacedlatching means extending from opposite sides of said frame means; and(b) elongated clip means adapted to releasably grip a heat sink and urgeit into thermal contact with the face of said device package oppositesaid leads, each end of said elongated clip means adapted to mate withone of said pair of latching means.
 2. Apparatus as defined in claim 1wherein said clip means comprises a body extending across said opencavity and includes a downwardly depending flange at each end thereofadapted to mate with one of said pair of latching means.
 3. Apparatus asdefined in claim 2 wherein said body of said clip means includes anarcuate section adapted to partially surround the post of the heat sinkbetween two of the radially extending fins.
 4. Apparatus as defined inclaim 1 wherein said clip means includes at least two upwardly extendingarms adapted to grip the heat sink about the lateral periphery thereof.5. Apparatus as defined in claim 4 wherein said upwardly extending armseach include an inwardly extending barb adapted to engage one of theradially extending fins of the heat sink.
 6. The combinationcomprising:(a) a heat sink having a plurality of spaced fins extendingradially from a central post; (b) an enclosed and sealed electronicdevice package having first and second oppositely disposed externalmajor faces and a plurality of leads extending substantially parallelfrom said second major face; (c) electrically insulating frame meanshaving a pair of spaced latching means extending from opposite sidesthereof and having an open cavity receiving and supporting said devicepackage therein with said leads projecting through said open cavity; and(d) elongated clip means urging said heat sink into thermal contact withsaid first major face of said .[.electronic.]. device package with eachend of said clip means releasably attached to one of said latchingmeans.
 7. The combination set forth in claim 6 wherein said clip meanscomprises a body extending across said open cavity and includes adownwardly depending flange at each end thereof mating with one of saidlatching means.
 8. The combination set forth in claim 7 wherein saidbody of said clip means includes an arcuate section partiallysurrounding said post of said heat sink between two of said fins.
 9. Thecombination set forth in claim 6 wherein said clip means is positionedbetween said frame means and said heat sink and includes at least twoupwardly extending arms grippingly engaging said heat sink.
 10. Thecombination set forth in claim 9 wherein each of said upwardly extendingarms includes an inwardly extending barb engaging one of the radiallyextending fins of said heat sink.
 11. Apparatus for mounting a heat sinkhaving a plurality of spaced fins extending radially from a central poston an electronic device package having a plurality of leads extendingsubstantially parallel from one surface thereof comprising:(a)electrically insulating frame means having an open cavity adapted toreceive and support an electronic device package about the peripherythereof with the leads extending from .[.the.]. .Iadd.said.Iaddend.device package through said open cavity and a pair of spacedlatching means extending from opposite sides of said frame means; and(b) elongated clip means including at least two upwardly extending armsadapted to releasably grip a heat sink about the lateral peripherythereof and urge it into thermal contact with the face of said devicepackage opposite said leads, each end of said elongated clip meansadapted to mate with one of said pair of latching means.
 12. Apparatusas defined in claim 11 wherein said upwardly extending arms each includean inwardly extending barb adapted to engage one of the radiallyextending fins of the heat sink.
 13. The combination comprising:(a) aheat sink having a plurality of spaced fins extending radially from acentral post; (b) an electronic device package having first and secondoppositely disposed major faces and a plurality of leads extendingsubstantially parallel from said second major face; (c) electricallyinsulating frame means having a pair of spaced latching means extendingfrom opposite sides thereof and having an open cavity receiving andsupporting said device package therein with said leads projectingthrough said open cavity; and (d) elongated clip means positionedbetween said frame means and said heat sink including at least twoupwardly extending arms grippingly engaging said heat sink and urgingsaid heat sink into thermal contact with said first major face of saidelectronic device package with each end of said clip means releasablyattached to one of said latching means.
 14. The combination set forth inclaim 13 wherein each of said upwardly extending arms includes aninwardly extending barb engaging one of the radially extending fins ofsaid heat sink. .Iadd.
 15. Apparatus for mounting a heat sink on anenclosed and sealed electronic device package having a plurality ofleads extending substantially parallel from one surface thereofcomprising:(a) electrically insulating frame means having an open cavityadapted to receive and support an electronic device package about theperiphery thereof with the leads extending from the device packagethrough said open cavity and a pair of spaced latching means extendingfrom opposite sides of said frame means; and (b) elongated clip meansadapted to releasably grip a heat sink and urge it into thermal contactwith the face of said device package opposite said leads, each end ofsaid elongated clip means adapted to mate with one of said pair oflatching means. .Iaddend..Iadd.16. Apparatus as defined in claim 15wherein said clip means comprises a body extending across said opencavity and includes a downwardly depending flange at each end thereofadapted to mate with one of said pair of latching means. .Iaddend..Iadd.The combination comprising:(a) a heat sink; (b) an enclosed and sealedelectronic device package having first and second oppositely disposedexternal major faces and a plurality of leads extending substantiallyparallel from said major face; (c) electrically insulating frame meanshaving a pair of spaced latching means extending from opposite sidesthereof and having an open cavity receiving and supporting said devicepackage therein with said leads projecting through said open cavity; and(d) elongated clip means urging said heat sink into thermal contact withsaid first major face of said device package with each end of said clipmeans releasably attached to one of said latching means. .Iaddend..Iadd.The combination set forth in claim 17 wherein said clip means comprisesa body extending across said open cavity and includes a downwardlydepending flange at each end thereof mating with one of said latchingmeans. .Iaddend.